Running blender from the command line
I'll be describing two approaches, one for the case that you don't know where the blender.exe is located, there other for when you do.

In case you don't know Blender's install directory:


Open the Windows Explorer WIN+E
Navigate to C:\Program Files\Blender Foundation\Blender and verify that the blender.exe is present. If it is continue with step 4, otherwise step 3.
In case you didn't find the blender.exe go back to C:\Program Files and use the search box to search for blender.exe. When it's found right click on the item and select Open File Location.
Click in the address bar that displays the current path and replace the text with cmd. Press enter and a command prompt should open with the working directory set to the path where Blender is located.




If you already know Blender's install directory:


Open a command line WIN+R and type cmd and press enter
If Blender is on a drive that isn't C: you will have to change to the correct drive. You can do this by typing the drive letter and pressing enter. For example if Blender is located in K:\05_Download\blender-2.80-windows64, you would type K: and press enter.
Change the directory to where Blender is located. Use cd to change the directory, for example cd K:\05_Download\blender-2.80-windows64.




Now you can start Blender with the (temporary) factory settings. Once you close and restart Blender without the flag it will load your preferences. This is better than doing a factory reset, when you only need to temporarily disable preference loading.

.\blender.exe --factory-startup


Another flag that is useful in case Blender crashes is --debug which will display debug information on the command line.

.\blender.exe --debug


The full list of command line arguments can be found in the manual.